ESR1 and breast cancer: Bazedoxifene (BZA) uniquely inhibits the growth of hormone-independent MCF-7:5C cells breast cancer cells by downregulating key proteins such as ERα and cyclin D1; this action distinguishes BZA from other selective estrogen receptor modulators, including raloxifene, 4-hydroxytamoxifen (4OHT), endoxifen (ENDOX), and fulvestrant [15].